 The complete alpha/310/pi transfer matrix includes weights for transitions between helix types as well as between helix and coil states.However, because 310 helices are much more common in the tertiary structures of proteins than pi helices, extension of the Lifson–Roig model to accommodate 310 helices - resulting in a 9x9 transfer matrix when capping is included - has found a greater range of application.Analogous extensions of the Zimm–Bragg model have been put forth but have not accommodated mixed helical conformations.